neuropsychiatric adverse reactions to mefloquine

Last reviewed 01/2018

  • the prevalence of neuropsychiatric adverse reactions is between 1 in 10,000 and 1 in 20,000 users of prophylactic mefloquine
  • risk is generally higher in females than males
  • mefloquine is contraindicated in patients at risk of seizures, epilepsy or psychiatric disease
  • mefloquine chemoprophylaxis should be used with caution in airline pilots
  • neuropsychiatric adverse reactions account for about 1/4 of side-effects associated with mefloquine
    • 41% of neuropsychiatric adverse reactions occur within one week of starting to take mefloquine
    • 69% of neuropsychiatric adverse reactions occur within two weeks of starting to take mefloquine
    • 78% of neuropsychiatric adverse reactions occur within three weeks of starting mefloquine chemoprophylaxis
  • the commonest symptoms are:
    • vertigo, dizziness and headaches
    • mood changes are a frequently reported symptom
  • serious adverse reactions include psychotic episodes, seizures, ataxia, hallucinations and depression

Roche have stated that (3):

  • Lariam (mefloquine) may induce potentially serious neuropsychiatric disorders

  • the most common neuropsychiatric reactions to mefloquine include abnormal dreams, insomnia, anxiety, and depression. Additionally hallucinations, psychosis, suicide, suicidal thoughts and self-endangering behaviour have been reported

  • do not use mefloquine for malaria chemoprophylaxis in patients with any active or a history of psychiatric disturbances

  • due to the long half-life of mefloquine, adverse reactions may occur and persist up to several months after discontinuation of the drug

  • healthcare professionals should react promptly to signs of neuropsychiatric reactions with mefloquine chemoprophylaxis. Mefloquine should be discontinued immediately and replaced by alternative malaria prophylaxis medication

  • advise patient that if they experience a neuropsychiatric reaction such as suicidal thoughts; self-endangering behaviour; severe anxiety; feelings of restlessness, confusion, or mistrust towards others; visual/auditory hallucinations; depression; or changes to their mental state during mefloquine chemoprophylaxis, they should stop taking mefloquine immediately and seek urgent medical advice


  • Prescribers' Journal (1999), 39 (3), 161-5.
  • Health protection agency 2007. Guidelines for malaria prevention in travelers from the United Kingdom
  • Roche (October 2013). Direct Helathcare Professional Communication on Larium (mefloquine) for malaria chemoprophylaxisis and the risk of neuropsychiatric adverse reactions